[maemo-developers] Frequencies scaling with OS2008

[From: Klaus.K Pedersen (Nokia-M/Helsinki)]

On Wed, 2008-01-09 at 11:19 +0100, ext Frantisek Dufka wrote:
[...]
> Just an update/explanation. I was not fuly aware of how it works. The 
> most important difference here that I missed previously is the term 
> 'dynamic dsp task'. I was not aware that there are also 'static' dsp 
> tasks. They look same from userspace but are linked statically to dsp 
> bios (?) and the clock policy ignores them (on purpose).

Yes. The idea is that when the DSP have to do real work it will load
a task to do it. The advanced and unknown tasks are loaded at runtime
as "dynamic tasks". 
So lacking a better way to predict the load of the DSP we are using
the number of these "dynamic tasks" to determine if the DSP require the
DSP_HI operation point (and thereby locking the ARM to 330MHz).


> So the pcm0/pcm1 dsp tasks are static but pcm2 is dynamic. Therefore 
> uncompressed audio output via pcm0/1 leaves the clock at 400 but same 
> output via pcm2 drops clock to 330. So maybe this is a bug and I should 
> report it in bugzilla? Maybe Real audio should use pcm0 or 1 or pcm2 
> should not be dynamic task?

True, all pcm tasks should be static. Please report it.


BR, Klaus
> 
> Frantisek